Positional suckiness?

So I have been having this issue, and it was highlighted even more so tonight. We were working on some basic guard passes and some defences when I noticed it. Each time that I would sit back in a good base, I would leave my head down or pointing towards the other guy. Each time he would be able to either goose neck me or pull me down by the lapel easily. I know that you are supposed to keep your head back or up, but how do you guys drill that into your heads? Is it just a passing stupidity that will one day remidy itself?

I never really understood the importance of body posture even in sitting in a combat base for an example.

Don't look at your opponent when in his guard. (it's not gay if you don't make eye contact) Look up and away, maybe 15% above parallel with your opponent or a bit less. This will naturally make your neck have strong posture. Feel everything, don't look at anything.